1. Field of the Invention
This invention relates to an image processing device and method and, in particular, to an image processing device and method for preventing the counterfeiting of bank notes, negotiable securities, and the like. The invention also relates to a copier including such an image processing device and method.
2. Description of the Related Art
The development in recent years of copying devices such as full-color copiers has enhanced the quality of reproduction to a level at which one cannot distinguish the copy from the original with the naked eye. Such faithful reproductions can now be obtained inexpensively. However, we must consider that along with this benefit comes the increased risk of copiers being put to such illicit uses as counterfeiting money, negotiable securities, and other original documents whose reproduction is legally prohibited. To avert this danger, various devices have been developed to prevent copiers from being used for counterfeiting. One such device is the image processing device disclosed in Patent Report 2-210481.
That image processing device reads the original image placed on the glass of the copier by scanning the entire original four times. It is used in full-color digital copy machines. Let us assume that a bank note has been loaded into the copy machine. On the first scan, the device detects the rough location of the watermark which identifies paper money, the item which the machine is to be prevented from copying, on the assumption that the document on the glass is, in fact, a bank note. On the second scan, the device detects the exact position of the bill and the angle at which it is placed, i.e., the exact position coordinates of the bill on the glass. On the third scan, the device calculates the position coordinates of the red seal stamped on the bill from the exact position of the bill obtained in the second scan. Based on these position coordinates, it extracts an image from the region in which the seal is placed, and it makes a judgment as to whether there is in fact a red seal on this item. By scanning the item several times, the device is able to detect whether or not the document loaded in the copier is one which it would be illegal to copy. If the device detects that a prohibited document such as a bank note has been loaded to be copied, it will perform its specified anti-counterfeiting operations on the fourth scan, such as making the entire display go black and preventing the copier from operating.
Since existing devices such as that described above require a number of scans to detect a bank note or other item which cannot be copied, arriving at a judgment is time-consuming. Furthermore, not all full-color copiers use a four-scan copying scheme like the one described above. Some scan the original three times, and others only once. The processing device described above cannot be used with these types of copiers. Another problem is that an extremely large memory capacity is needed merely to store data concerning the size of paper money. Inevitably, then, only a limited number of kinds of money can be detected.